Machines with work implement systems actuated with hydraulic circuits and hydraulic cylinder assemblies may size hydraulic control valves to allow operators more control when work implements are subject to over-running loads. This sizing of control valves may also allow fine control of work implement movements during operation. Although smaller cross-sectional areas of control valves may allow better control during certain work conditions, they may be less power efficient and slower to respond in comparison to larger cross-sectional areas of control valves, when work implements encounter resistive loads.
United States Patent Application Publication US 201010024410 A1 filed by Brickner discloses a hydraulic system for a machine. The hydraulic system includes an actuator with a first chamber and a second chamber, a first valve, a second valve, a third valve, and an operator input device displaceable from a neutral position to generate a signal indicative of a desired movement of the actuator. The hydraulic system further includes a controller configured to open the first and third valves by amounts related to a signal to pass fluid, and open the second valve by an amount related to the signal to pass fluid when the signal indicates a desire for increased actuator velocity. The third valve may continue to open during opening of the second valve.